The Wall Street Journal has pulled together a map of where radiation has been found in America. With EPA centers scattered throughout the country, the prevalence of radiation was mostly found on the West and East Coast. So what’s the rationale behind that? Are those areas simply the densest population-wise, or does it have to something with the fact they are often hubs for international travel?

Still, Eric Matus, a radiation physicist, says that, “The levels that we’re detecting are extremely, extremely low—we’re talking about many orders of magnitude below what we would consider a risk.”